System for retrieving a gas phase sample from a gas stream containing entrained liquid, and sample conditioner assembly therefore

ABSTRACT

A system for the retrieval and initial conditioning of sample gas for “on line” analyzers or filling of gas sample cylinders. The preferred embodiment of the present invention contemplates a system configured to obtain a representative gas phase sample from a process gas containing entrained liquid, or a process gas which generally is highly susceptible to partial condensation of some gas phase components. The preferred embodiment of the present invention teaches an assembly including a phase separation membrane and housing configured to facilitate the removal of entrained liquid from a sample gas stream. Accuracy of the sample is enhanced, and compositional changes are avoided by first extracting a sample from the process gas followed by removal of entrained liquid it may contain, with the entrained liquid removal being conducted at the prevailing process gas pressure and temperature. Thereafter the liquid free sample may be desaturated by lowering its pressure to reduce its susceptibility to condensation.

REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 08/701,406, filed Aug. 22, 1996, indicating as theinventor Donald P. Mayeaux, entitled “Modular Sample ConditioningSystem”, and now U.S. Pat. No. 5,841,036.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the sampling of process fluids such asimplemented by petrochemical plants, refineries, gas separation plants,natural gas pipelines, etc, and in particular to the collection andinitial conditioning of sample gas for “on line” analyzers or filling ofgas sample cylinders.

The preferred embodiment of the present invention contemplates a systemconfigured to obtain a representative gas phase sample from a processgas containing entrained liquid, or a process gas which generally ishighly susceptible to partial condensation of some gas phase components.

The preferred embodiment of the present invention teaches an assemblyincluding a phase separation membrane and housing configured tofacilitate the removal of entrained liquid from a sample gas stream.Accuracy of the sample is enhanced, and compositional changes areavoided by first extracting a sample from the process gas followed byremoval of entrained liquid it may contain, with the entrained liquidremoval being conducted at the prevailing process gas pressure andtemperature. Thereafter the liquid free sample may be desaturated bylowering its pressure to reduce its susceptibility to condensation.

BACKGROUND OF THE INVENTION

The heating value of natural gas has a significant impact on itsmonetary value. In general, the heating value of natural gas increasesas the concentration of low volatility, high molecular weight componentsincreases. Condensation of gas phase components, which reduce theproportion of high molecular weight components, therefore tends todecrease gas phase heating value while vaporization of entrained liquidhas the opposite effect.

In order for natural gas supply to balance with demand over the next 10to 20 years it will be necessary to increase production from deep-waterfields in the Gulf of Mexico. (Refer to Volume 1, Fall/Winter 1997official newsletter of Colorado Engineering Experiment Station Inc.) Gasproduced from deep-water fields, containing higher concentrations of lowvolatility components such as water vapor and heavy hydrocarbons, has ahigher susceptibility to condensation than shelf and onshore productiongas.

Additionally, some onshore produced gas, particularly in low ambienttemperature regions, frequently contain entrained liquids. Other liquidswhich can influence vapor phase composition when fluid pressure ortemperature changes occur are glycols and amines which are carried overinto the gas phase from gas contactors designed to remove water vaporand acid gases respectively.

A Joint Industry Project (JIP) is underway to address problemsassociated with measurement and transportation of “wet gases”. A part ofthe JIP focus will include improvement of wet gas sampling techniques.

The American Petroleum Institute (API) and the Gas ProcessorsAssociation (GPA) are two leading industry organizations havingrecommended standard practices for sampling and analysis of natural gas.Both recommend that entrained liquids are to be removed from natural gassamples at prevailing source gas pressure and temperature. (Refer toManual of Petroleum Measurement Standards chapter 14-Natural Gas fluidsmeasurement, section 1 collecting and handling natural gas samples forcustody transfer, fourth edition, August 1993.) This is done to preventgas phase compositional changes caused by vaporization and condensation.

Following the recommended practices has been almost impossible due tolack of available hardware to accomplish the task. For example GPArecommends a separator design (FIG. 6 in the aforementioned APIdocument) which at best is suited for removal of liquid slugs and largedroplets, neither, of which cause frequent sampling problems.Furthermore, there is no provision for maintaining process source gastemperature. Liquid aerosol, which are the most frequent source ofliquid entrainment, are not easily separated from sample gas by this“Knock-Our” type of GPA separator.

Conventional mechanical coalescer elements constructed of fibers,screens, etc. require gas flow thru the element for aerosol coalescingto occur. In most cases this precludes the return of the coalescedliquid to the process gas source at the original source pressure. Withincreasing environmental concerns disposal of the coalesced liquid canpresent serious problems if it cannot be returned to the originalsource.

Gas phase separation membranes are known and utilized in stack and fluegas analyzers for removal of entrained water, sub-micron aerosols, andfiltration of ultra-fine particulates; examples of such membranesinclude the gas phase separation membranes utilized in the GENIE Series100 line from A+ Corporation of Prairieville, La. USA. However, theutilization of said membranes is not believed contemplated inconjunction with the system of the present invention.

GENERAL SUMMARY DISCUSSION OF THE INVENTION

Unlike the prior art, the present, searched for invention provides asystem for retrieving a gas phase sample from a gas stream containingentrained liquid, in a cost effective highly accurate, and generallyeasily implemented fashion, providing a gas sample at the prevailingprocess gas source pressure and temperature condition, therebypreventing gas phase composition changes. The subject invention, asample conditioner assembly, provides a coalescer design that overcomesthe problems associated with prior art systems, methods, and hardware.

The preferred embodiment of the present invention contemplates sampleconditioning wherein there is provided a coalescing assemblyparticularly suited for coalescing, which employs a phase separatingmembrane for the removal of liquid entrained in sample gas.

In the first operating mode of the preferred embodiment of the presentinvention, this coalescing assembly is positioned external to theprocess source gas, and coalesced liquid separated by a phase separatingmembrane is returned to said process source gas by gravity free flow. Ina second operating mode of this preferred embodiment of the presentinvention coalesced liquid, drained from the coalescing assembly, isdisposed by piping to a location external to the original process sourcegas.

In accordance with a second embodiment of the present invention, thecoalescing assembly is inserted into a housing, said housing and phaseseparating membrane portion of said coalescing assembly being positionedwithin the containment walls of a process source gas vessel or pipeline.A means is provided for inserting and withdrawing the coalescingassembly from said housing during which time said housing is insertedinto a pressurized process source gas. This feature facilitates theinspection or replacement of the coalescing element which consists of aphase separating membrane.

Additionally, a valving means positioned in the lower end of saidhousing is actuated to a closed position by the withdrawal of saidcoalescing assembly which provides isolation and containment of theprocess source gas. Said second embodiment of the present invention hasthreaded means to facilitate said insertion and withdrawal of thecoalescing assembly from said housing even when the process source gasis at elevated pressure.

In the third embodiment of the present invention, a pressure reducingregulator is integrated into said coalescing assembly of said secondembodiment of the present invention.

In the preferred, second, and third embodiment of the present invention,the phase separation membrane employed repels aqueous and organicliquids while remaining permeable to gas.

Further, in the preferred, second, and third embodiment of the presentinvention, a support member, placed immediately upstream of said phaseseparation membrane protects the unit against physical damage which mayotherwise occur if fluid flow is inadvertently reversed during a startupor shutdown operation.

A major advantage of the preferred, second, and third embodiment of thepresent invention over prior art, is that liquid entrained in a gas isremoved at essentially the prevailing process gas source pressure andtemperature condition, thereby preventing gas phase composition changes.A second advantage is that the insertion means, consisting of therotation of a threaded member is safe, simple, and economical.

The advantage offered by the third embodiment is that pressure reductionor regulation occurs after entrained liquid has been removed therebypreventing gas phase compositional changes.

The system of the present invention may also be utilized in conjunctionwith conventional sampling and analyzation techniques includingisokinetic sampling and gas chromatography analysis, for example, todiscern the amount of entrained liquid in a gas stream. In this regard,a sample of the gas stream would be processed with the present inventionto remove entrained liquid therefrom, and this data from this samplewould be compared with data obtained on said gas stream utilizingtraditional sampling techniques, thereby allowing the user to discernthe amount and type of entrained liquids removed from the stream,thereby providing an enhanced analysis of the gas stream.

In the article Effect of Entrained Liquid on Orifice Measurement by V.C. Ting, as presented in the 1998 proceedings of the American School ofGas Measurement Technology (1998, pp 85-88), Dr. Ting recognizes thatstandard orifice meter measurement of gas flow in a gas stream can beaffected by a small amount of liquid entrained in the orifice meter,thereby calling into question the accuracy of said technique, which iswidely utilized and relied upon in the industry. Conversely, the presentinvention provides a relatively cost effective and reliable system toprovide detailed analysis as to the amount and content of entrainedliquid within a gas flow, allowing the user to compensate for saidentrained liquids in discerning gas flow measurements, as well asproviding a detailed inventory of the composition of entrained liquid ofthe gas flow.

It is therefore an object of the present invention to provide a sampleconditioning assembly that provides a gas sample at the prevailingprocess gas source pressure and temperature condition, therebypreventing gas phase composition changes

It is a further object of providing a method of sampling a gas from agas stream having entrained liquid, wherein the gas sample is maintainedat the prevailing process gas source pressure and temperature condition,thereby preventing gas phase composition changes.

It is another object of the present invention to provide a system forsampling gas from a gas stream which is more accurate, cost effective,and more easily implemented and maintained than prior art systems.

Lastly, it is an object of the present invention to provide a method foraccurately sampling a gaseous hydrocarbon stream having entrained liquidtherein, in order to accurately discern the properties thereof.

BRIEF DESCRIPTION OF DRAWINGS

For a further understanding of the nature and objects of the presentinvention, reference should be had to the following detaileddescription, taken in conjunction with the accompanying drawings, inwhich like parts are given like reference numerals, and wherein:

FIG. 1 is a side, cross sectional view of the first, preferredembodiment of the sample conditioning assembly of the present invention.

FIG. 2 is a side, cross sectional view of the invention of FIG. 1,illustrating the location of passage (14) relative to ports (19, 20),and groove (15).

FIG. 3 is a side, cross, sectional view of the second operating mode ofthe preferred embodiment of FIG. 1, illustrating the operation thereof.

FIG. 4 is a side view of a housing configured to thermally insulate acoalescing assembly (shown in phantom).

FIG. 5 is an end view of the illustration of FIG. 4

FIG. 6 is a side, partially cut-away, partially cross-sectional view ofthe second embodiment of the invention of FIG. 1, illustrating housingassembly (43) and coalescing assembly (44).

FIG. 7 is a side, partially cut-away, partially cross-sectional view ofthe invention of FIG. 6, illustrating the opening of poppet assembly(69) in an open position.

FIG. 8 is a side, partially phantom view of the invention of FIG. 6,illustrating the housing assembly (43) removed from the coalescingassembly (44).

FIG. 9 illustrates a the invention of FIG. 8, with the internalcomponents in phantom, affixed to coalescing assembly (44).

FIGS. 10 and 10A illustrate an end view of the invention of FIG. 6installed into a pipeline having a fluid stream, wherein entrainedliquid is shown draining from valve housing cavity, and wherein gasphase flows through phase separation membrane (59), up to an analyzer orstorage container, etc.

FIG. 11 is an exploded view of the sample conditioning assembly (72) ofFIG. 10, illustrating the housing.

FIG. 12 is an exploded view of the sample conditioning assembly of ofFIG. 11, illustrating the valve assembly, springs, membrane, andinternal components.

FIG. 13 is a partially cut-away, partially cross-sectional, side view,illustrating a third embodiment of the invention of FIG. 1, providingpressure regulation.

FIG. 14 is a partially cut-away, partially cross-sectional, side view,illustrating the invention of FIG. 13, indicating in phantom the area ofFIG. 14A.

FIG. 14A is a side, partially cross-sectional, partially cut-away viewof an area indicated in FIG. 14.

FIG. 15 is a side, partially cut-away, partially cross-sectional,assembled view of the invention of FIG. 12.

DETAILED DISCUSSION OF THE INVENTION

Referring to FIGS. 1 and 2, the preferred, first embodiment of theinvention contemplates a sample conditioning assembly 41, utilizing acircular sheet of phase separation membrane 1, inlet plate 2, and outletplate 3, sample conduit 4, block valve 5, sample conduit 6, membranesupport 17, and sample conduit 38.

A passage 14, located in inlet plate 2, extends between port 19 and port20. A circular groove 15, in the outer face 23 of inlet plate 2,intersects passage 14 at point 24 and point 25. Membrane retention plate26, formed on face 23 of inlet plate 2 is circumscribed by circulargroove 15. Port 19, Port 20 and Port 21 are threadingly adapted forreceiving sample conduit 4, sample conduit 38, and plug 27.

A segment 10 of sample conduit 6 is threadingly adapted for attachmentto threaded member 32 located on containment wall 7 of process gassource 9. Block valve 5 is in series fluid communication with sampleconduit 4 and sample conduit 6. Sample conduit Segment 33 of sampleconduit 6 extends, thru containment wall 7, with its opening 34, intoprocess gas source 9.

In relation to a first operation mode of said first embodiment, samplegas 36 of process gas stream 9, containing entrained small and aerosolsized liquid droplets 8, enters opening 34 of sample conduit segment 33,flows thru conduit 6, block valve 5, conduit 4, port 19, passage 14 andcircular groove 15 then into inlet cavity 16, wherein the gas phase ofsample gas 36 flows thru phase separating membrane 1, membrane support17, outlet cavity 18, port 21, sample conduit 38 and thereon to anexternal analyzer, sample storage container or other sample conditioningcomponent not shown. Liquid droplets 8, entrained in the gas phase, arerejected by phase separating membrane 1, wherein said droplets 8coalesce into larger droplets and/or film 13, gravity flows into thelower end 35 of inlet cavity 16, circular groove 15 and flows downwardthru port 19, along sample conduit 4, block valve 5, sample conduit 6,sample conduit segment 33, thru opening 34 and thereon into process gassource 9.

Empirical testing revealed that a liquid film, composed of 80%isopropanol and 20% water by volume, can flow downward in a gas conduitsimultaneously with an air stream flowing upward thru said gas conduitat velocities not exceeding seventeen feet per second and provided thatthe internal diameter of said gas conduit is not less than 0.25 inches.

Referring to FIG. 3, a second operating mode of the first embodimentcontemplates said first embodiment sample gas 36, of process gas stream9, containing entrained liquid droplets 8, entering opening 34 of sampleconduit segment 33, flowing thru conduit 6, blocking valve 5, andconduit 11, then entering port 20, flowing into passage 14, wherein aportion of said process gas flows thru circular groove 15, inlet cavity16, phase separation membrane 1, membrane support 17, outlet cavity 18,port 21, sample conduit 38, and thereon to an analyzer, sample storagecylinder or other sample conditioning component not shown. Liquidaerosol droplets 8, entrained in the gas phase, are rejected by phaseseparation membrane 1, wherein it is coalesced into larger dropletsand/or film 13, gravity flows into the lower end 35 of inlet cavity 16,circular groove 15 and into passage 14.

A second portion of said sample gas 36, containing entrained liquiddroplets 8 and entering passage 14, from port 20, flows directly to port19 wherein it combines with coalesced droplets and/or film 13, exitsport 19, enters conduit 12, and thereon flows to an external destinationnot shown. Said second operating mode provides a means for removal ofentrained liquid without distortion of the gas phase composition,decreases the sample transport time, and also provides an alternatemethod for disposal or analysis of coalesced entrained liquid when itsreturn to the process gas source is not possible, necessary, ordesirable. Passage 14 provides a means for bypassing a portion of samplegas 36, internal to coalescing assembly 41, said portion of sample gas36 not being exposed to phase separating membrane 1.

In relation to the first and second operational modes of the firstembodiment of the present invention, coalescing and removal of entrainedliquid is accomplished at or near the prevailing process sourcepressure. To prevent gas phase distortion from occurring, the process ofcoalescing and removing of entrained liquid must also be carried out atessentially the prevailing process source temperature. There are severalmeans by which a coalescing assembly may be maintained at essentiallythe prevailing process source temperature. One such means is shown inFIG. 4 and FIG. 5, where coalescing assembly 41 is shown internal tohousing cavity 40 of thermally insulated housing 22.

Thermal insulation skirt 30 envelopes or surrounds process gas sourcevessel 7 from a first point 28 to a second point 42 laterally along saidprocess gas source vessel 7. An insulated segment 29 of process gassource vessel 7 provides a means for exchange of heat between housingcavity 40 and process fluids 9. Heat exchange enhancement may beaccomplished by several other means not shown which includes increase ofthermal radiation surface by either increasing the area of uninsulatedsegment 29 or by employment of conventional heat sink attached touninsulated segment 29.

For example, containing with FIG. 5 a heat pipe, not shown, having firstand second, the second end communicating with the process gas sourcevessel 7 may also be employed singularly or in combination with othermeans for enhancement of heat transfer between housing cavity 40 andprocess fluids 9. Coalescing assembly 41, housed within housing cavity40, will remain at essentially the temperature of process fluid 9,providing that there is sufficient heat transferred from process fluid 9to housing cavity 40 to offset heat transfer thru insulated housing 22.Insulation skirt 30 permits uninsulated segment 29 to achieveessentially the temperature of process fluid 9 by negating the influenceof the local ambient temperature.

FIGS. 6-8, 11-12, and 15 disclose a second embodiment 72 of the presentinvention, illustrating a housing assembly 43 and coalescing assembly44. In combination, valve assembly 47 and housing 68 comprise housingassembly 43. Valve assembly 47 comprised of stem 48, poppet body 49, “O”ring 50, seat 51, spring 52, snap ring 53, washer 92, O ring 94, andvalve housing 45, is attached to lower section 46 of housing 68 by malethreads 54 and female threads 55. Coalescing assembly 44 is comprised oftubular stem 56, retaining bolt 57, porous membrane support 58, washer65, phase separating membrane 59, O ring 60, O ring 61, rod 62, rod 63,snap ring 66, retaining washer 106, right threaded nut 64, and thrustwasher 67. Rods 62 and 63 press fit into holes 92 a and 92 b (FIG. 7)respectively said holes being formed in the outer surface of tubularstem 56.

With coalescing assembly 44 removed from housing assembly 43, as shownin FIG. 8, poppet assembly 69, comprised of stem 48, poppet body 49, andO ring 50; urged by the expansion of spring 52, travels upwards untilcontact of O ring 50 is made with seat 51, thereby forming a first fluidbarrier between valve housing cavity 70 and membrane cavity 71 (FIGS. 6and 7).

When coalescing assembly 44 is fully reinserted into housing assembly43, as shown in FIG. 6, the downward force exerted by the head 73 ofretention bolt 57 upon stem 48 forces poppet assembly 69 downward;thereby breaking contact between O ring 50 and seat 51 andreestablishing fluid communication between valve housing cavity 70 andmembrane cavity 71.

O ring 60 and O ring 61, in combination with inner wall 77 of housing 68form a second fluid barrier between membrane cavity 71 and upper housingcavity 74, said fluid barrier being first formed during the insertion ofcoalescing assembly 44 into housing assembly 43 (Refer to FIG. 9), andat which time O ring 61 contacts inner wall 77 at point 76. Whencoalescing assembly 44 is inserted into housing assembly 43 until thehead 73 of retention bolt 57 first contacts stem 48, as shown in FIG. 7,O ring 60 and O ring 61 are both in contact with inner wall 77 and forman effective said second fluid barrier between membrane cavity 71 andupper housing cavity 74, said second fluid barrier being formed beforecontact is broken between O ring 50 and seat 51.

The length relationship between coalescing assembly 44 and housingassembly 43 is such that said second fluid barrier is established at alltimes during insertion or withdrawal of coalescing assembly 44 to orfrom housing assembly 43 wherein O ring 50 is not in contact with seal51 and fluid communication is established between valve housing 70membrane cavity 71, and process gas source 78 (Refer to FIG. 10). Upperhousing cavity 77, open to the atmosphere, is at or near atmosphericpressure.

Right threaded nut 64 (Refer to FIG. 6), when engaged with male threads80 on housing 68 and rotated clockwise, exerts a downward force uponthrust washer 67, rod 62, rod 63, forcing the entire coalescing assembly44 downward, thereby overcoming the upward force exerted by spring 52and the action of process gas source 78 (Refer to FIG. 10) pressureagainst the lower surfaces of coalescing assembly 44.

Counterclockwise rotation of right threaded nut 64 facilitates thewithdrawal of coalescing assembly 44 from housing assembly 43. Slot 81 aand slot 81 b in the wall of housing 68 guide rod 62 and rod 63 toprevent rotation of coalescing assembly 44 as it is inserted orwithdrawn into or from housing assembly 43. Closed end 82 a of slot 81 aand closed end of 82 b of slot 81 b acting on rod 62 and rod 63, limitthe downward travel of coalescing assembly 44 into housing assembly 43to insure that spring 52 is not over compressed by overtravel of poppetassembly 69.

Continuing with FIGS. 10 and 10A, in operation, sample conditioningassembly 72 is inserted thru and attached to pipe or vessel wall 79, andhas its lower section 46 and valve assembly 47 immersed into apressurized process gas source 78 as shown in FIG. 10. a small slipstream of process gas source gas 78 containing entrained liquid 89enters valve housing cavity 70 by way of openings 83 a and 83 b, flowsupward thru annulus 84, formed between the inner diameter of seat 51 andouter diameter of stem 48, then into membrane cavity 71, wherein the gasphase flows thru phase separating membrane 59, membrane support 58,threaded passage 119, which is formed by threads in retaining bolt 57,passage 85, passage 86, bore 87 of tubular stem 56, outlet port 88 andthereon to an external analyzer, sample storage container, or othersample conditioning component not shown. Entrained liquid 89, in the gasphase is rejected by phase separating membrane 59, coalesces into largedroplets 90 and or film 91, wherein it gravity flows thru the annulus84, into valve housing cavity 70, then thereon thru openings 83 a and 83b thereby returning to process gas source 78.

The physical dimension relationship between the internal diameter ofseat 51 and the outer diameter of stem 48 which form annulus 84, issufficient to insure that coalesced liquid droplets 90 and film 91 cangravity flow downward thru said annulus 84 during which time aslipstream of process gas source 78 is flowing upward thru said annulus84. Empirical testing has shown that an annulus of 0.10″ formed betweenthe internal diameter of seat 51 and the outer diameter of stem 48having a minimum cross sectional area of 0.05 square inches issufficient to conduct a downward flow of 10 cubic centimeters per minuteof liquid film composed of 80% isproponal and 20% water by volume and anupward flow of gas at a velocity not exceeding 15 feet per minute.

Said liquid flow rate and gas velocity condition being satisfactory forthe intended applications of sample conditioning assembly 72.

Phase separating membrane 1, of the first embodiment and phaseseparating membrane 59 of the second and third embodiment may utilizethe a phase separation membrane as provided by A+ CORP of Prairieville,La., for example, type 6 membranes as utilized in the GENIE Series 100membrane separators.

In order for a membrane to be useable in the separation of entrainedliquid in sample gas as required by the present invention it mustexhibit certain characteristics such as: (a) not becoming wetted by theentrained liquid, this characteristic is required for surfacecoalescing; (b) rejecting entrained liquid at the operating differentialpressure across the membrane which is required to produce the desiredgas flow rate thru the membrane, this characteristic is needed toprevent liquid flow thru the membrane; c) having essentially the samepermeability or flux rate for all components of a sample gas mixture,this characteristic is required to prevent alteration of the gas phasecomposition during its passage thru the membrane; (d) having sufficientgas permeability so that the required flow rate of sample gas thru themembrane can be produced at low membrane differential pressure, thischaracteristic is required to minimize the membrane area requirements.

Laboratory analysis, conducted by a gas chromatograph based BTU analyzerof pipeline quality natural gas sample, is shown in Table II.

TABLE II Natural Gas Analysis in Mole % - Laboratory Analysis Analysis AAnalysis B Analysis C C₆ Plus 0.4128 0.4188 0.4148 Propane 2.5814 2.57962.5789 I-Butane 0.9706 0.9694 0.9708 N-Butane 0.6714 0.6697 0.6710Neopentane 0.0097 0.0098 0.0099 I-Pentane 0.3019 0.3001 0.3028 N-Pentane0.1903 0.1881 0.1901 Nitrogen 0.1389 0.1354 0.1384 Methane 87.194687.2045 87.1967 Carbon Dioxide 1.4522 1.4522 1.4541 Ethane 6.0761 6.07276.0724 Dry Gross BTU 1154.39 1154.45 1154.42

Analysis A—Baseline analysis of natural gas sample utilized for analysisB,C,D, and E.

—Sample gas did not flow thru a phase separation membrane.

Analysis B—Gas flowed thru A+ Corp Type 6 membrane from membrane sourcea. a bypass cross flow rate of 900 cc/min. also flowed simultaneouslyacross the membrane surface.

Analysis C—Gas flowed thru A+ Corp Type 6 membrane from membrane sourcea. There was no bypass cross flow.

By comparing results of analysis A, B, & C, it can be seen that the A+Corporation membrane Type 6 did not induce any appreciable changes inthe composition or BTU value of natural gas sample flowing thru saidmembrane.

Tests were conducted on rich gas samples having BTU values of 1250 BTUand 1500 BTU by Southwest Research Institute, who is sponsored by theGas Research Institute and overseen by American Petroleum Institutechapter 14.1 working group. The interim research results, issued inApril 1998 by Southwest Research Institute, reflect less than 0.25%,distortion in gas density, (a reflection of the molecular weight) orheating value, (BTU value) in said 1250 BTU and 1500 BTU gas samplesmade to flow thru A+ Corp Type 6 membrane from membrane source a beforeentering the analyzer.

Field results, conducted on membrane from membrane source C and A+ CorpType 6 membrane from source a supported the aforementioned laboratoryanalysis.

In addition to providing enhanced sampling of the gas sample from thefluid stream vis a vis removal of entrained liquid therefrom, thepresent system may be utilized to facilitate detailed analysis of thecontents and amount of entrained liquid in the fluid stream, whencoupled with traditional sampling techniques. The system of the presentinvention may also be utilized in conjunction with conventional samplingtechniques including isokinetic sampling, to discern the amount ofentrained liquid in a gas stream, utilizing a sample from said gasstream containing a proportionate amount of liquid as found in said gasstream. In this regard, a sample of the gas stream would be processedwith the present invention to remove entrained liquid therefrom, andthis data from this sample would be compared with data obtained on saidgas stream utilizing traditional isokinetic sampling techniques, toobtain a gas sample containing an amount of liquid proportional to thatcontained in the source stream, allowing the user to discern the amountand type of entrained liquids removed from the stream, thereby providingan enhanced sampling of the gas stream.

In practicing the method of discerning the contents and amount ofentrained gas in the fluid stream utilizing the system of the presentinvention, one may: 1) perform conventional analysis of the fluid streamutilizing isokinetic or other analysis technique to discern the velocityand mass of the components of the stream; 2) sample said fluid streamutilizing the apparatus of the present invention, providing sample gashaving the entrained liquid removed therefrom; and 3) applyingcomparative analysis of the data from (1) and (2) to discern the amountof entrained liquid removed from the gas, thereby discerning the liquidto gas ratio, liquid mass, composition, quantity, quality, and BTU valueof the stream, of a combined or homogeneous stream.

A similar method of method of discerning the composition or amount ofentrained fluid in a fluid stream containing vapor and entrained liquid,could include for example, the steps of:

a. obtaining a first representative sample of said fluid streamcontaining both vapor and entrained liquid in amounts representative ofsaid fluid stream at prevailing temperature and pressure conditions;

b. obtaining a second representative sample of gas in vapor phase fromsaid fluid stream, under prevailing temperature and pressure conditions;

c. vaporizing said entrained liquid in said first representative sample,while maintaining said vapor present in obtaining said firstrepresentative sample, so as to produce a homogeneous vapor phasesample;

d. analyzing said second representative sample, providing vapor phasedata on vapor in said fluid stream at prevailing pressure andtemperature conditions;

e. analyzing said homogenous vapor phase sample, obtaining homogenousvapor/liquid data on the composition of said fluid stream;

f. comparing said vapor phase data and said vapor/liquid data, anddiscerning the differences thereof.

This method could be utilized to discern the amount, or composition ofentrained liquid present in said fluid stream.

Gas chromatography may well be a preferred method of analysis in thisregard, although various conventional methods exist, some of which maybe preferable over others, depending upon the circumstances.

Another alternative analysis under the invention of the present systemcould include collecting the liquid drained from the membrane area,allowing the user to measure the amount and composition of saidentrained liquid in the fluid stream.

A third embodiment 106 of the present invention (Refer to FIG. 13 andFIG. 14) is comprised of aforementioned housing assembly 43 andcoalescing/pressure reducing assembly 95. Said coalescing/pressureregulator assembly 95 is comprised of tubular stem 96, rod 97, ball 98,spring 99, nut 107, lower housing 100, upper housing 101, diaphragm 102,spring 103, and handle 105, retaining bolt 57, washer 65, membranesupport 58, phase separating membrane 59, O ring 60, O ring 61, rod 62,rod 63, right threaded nut 64, and thrust washer 67. In addition to thecoalescing and entrained liquid removal function provided by secondembodiment 72, said third embodiment 106 provides the additionalfunction of pressure regulation.

A small slip stream of process source gas 78, at process gas sourcepressure and made free of entrained liquid by the second embodimentcoalescing process previously described, exits passage 86 thru a centerhole in nut 107, enters spring cavity 108, flows between ball 98 andseat 110, passage 112, then thru annulus 109 formed by the outerdiameter of rod 97 and inner diameter of cavity 113 of tubular stem 96,enters diaphragm cavity 114 and then exits by flowing thru passage 115,port 116, and conduit 117 thereon to an external analyzer or samplestorage means not shown.

The pressure of sample gas in diaphragm cavity 114 acting againstdiaphragm 102 produces an upward force against spring 103. Thedecompression of spring 52 produces an upward force against ball 98,lower rod segment 111, and rod 97 which serves to maintain contactbetween rod 97 and diaphragm 102. Handle 105 has a right threaded member104 which is threadingly engaged in female threads 118. The gas pressurein passage 112, annulus 109, and diaphragm cavity 114 is regulated byaltering the distance between ball 98 and seat 110. In operation handle105 is rotated clockwise to increase or counter clockwise to decreasethe gas pressure set point.

Rotation of the handle clockwise compresses spring 103 therebyincreasing the downward force applied to the upper surface of diaphragm102. Said downward force, acting upon the diaphragm 102, rod 97, lowerrod segment 111 forces ball 98 downward, thereby increasing its distancefrom seat 110 resulting in greater gas flow into diaphragm cavity 114and increasing the gas pressure at all points downstream of ball 98 andseat 110.

Said increase in pressure results in increasing the upward force exertedby diaphragm 102 against spring 103. When the upward force resultingfrom the gas pressure acting on diaphragm 102 is equal to the downwardforce exerted by spring 103 the gas pressure is deemed to be at its setpoint. Changes in flow rate thru conduit 117 results in a momentary gaspressure change in diaphragm cavity 114.

Said momentary pressure change causes a movement of diaphragm 102 in adirection and magnitude which will change the distance relationshipbetween ball 98 and seat 110 and restore the gas pressure to its setpoint.

The aforementioned pressure regulation method and its many variationsare well known to those skilled in the art and it is also well knownthat gas pressure regulators which can be inserted into a pressurizedvessel are commercially available. Two well known sources of theseinsertion type of gas regulators are Welker Engineering Company ofSugarland, Texas and YZ Industries of Snyder, Tex.

Insertion gas pressure regulators are typically utilized for preventingcondensation of hydrocarbons resulting from the Joule-Thompson coolingwhich occurs during the pressure reduction of a gas. The insertion gaspressure regulator's design provides for the pressure letdown to occurin a segment of said pressure regulator which is inserted in the gassource vessel. The gas surrounding said segment of the gas pressureregulator functions as a heat sink and prevents the gas temperature fromlowering excessively during said pressure letdown.

However there is no provision in said pressure regulators for coalescingand removing aerosol droplets from the gas before pressure letdownoccurs. As previously mentioned, the presence of liquid in any dropletsize or form in a sample gas undergoing either a pressure or temperaturechange will change the gas phase composition. Mr. Thomas F. Welker, ofWelker Engineering Company, in a presentation made at the AmericanSchool of Gas Measurement Technology in Houston Texas in September of1997, teaches that liquid contaminates may be put in flight by highturbulence in the source gas and that said contaminates may then becomeingested into the probe regulator (another term for insertion type ofgas pressure regulator) and thereby become part of the sample.

He further teaches that said liquid contaminates should not become apart of the sample gas stream and should therefore not be analyzed. Histeachings are consistent with aforementioned API and GPA recommendedstandard practices.

The major benefit of the third embodiment of the current invention isthat it provides a means for removal of entrained liquids at prevailingprocess pressure and temperature, before reduction of the gas pressure.Said gas pressure reduction being performed in a region within probehousing 43 whereby heat sinking to the process gas source or itscontainment wall occurs.

In FIG. 13 it can be seen that the ball 98 and seat 110 are in closeproximity to threaded engagement area 75 of housing 43 to vessel 79.This approach prevents flashing of entrained liquids, which causes gasphase alteration, and minimizes cooling of the gas during pressurereduction which prevents condensation of some gas phase components andadditional gas phase alterations.

The invention embodiments herein described are done so in detail forexemplary purposes only, and may be subject to many different variationsin design, structure, application and operation methodology. Thus, thedetailed disclosures therein should be interpreted in an illustrative,exemplary manner, and not in a limited sense.

What is claimed is:
 1. A sample conditioning assembly for separation andremoval of entrained liquid from gas in a fluid stream, comprising: aninsertion assembly having a fluid conduit having first and second ends;a housing having first and second ends, said housing further formed toreceive said insertion assembly; a phase separation membrane situated inassociation with said insertion assembly, said phase separation membranehaving first and second sides, said phase separation membrane configuredto allow the passage of gas therethrough, while coalescing entrainedliquid from said gas, so as to provide filtered gas from said secondside of said phase separation membrane, while providing coalesced liquidat said first side of said phase separation membrane; a valve, saidvalve formed to open when said insertion assembly is inserted into saidhousing so as to allow the migration of gas from said fluid stream tosaid first side of said phase separation membrane, said valve configuredto close when said insertion assembly is removed from said housing. 2.The sample conditioning system of claim 1, wherein said coalesced liquiddrains through said open valve into said fluid stream.
 3. The sampleconditioning system of claim 1, wherein said filtered gas passes throughsaid fluid conduit formed in said insertion assembly to a sample storagecylinder.
 4. The sample conditioning system of claim 1, wherein there isfurther provided a pressure regulator associated with said fluid conduitin said insertion assembly downstream of said second side of said phaseseparation membrane.
 5. The system of claim 4, wherein said pressureregulator is adjustable.
 6. The system of claim 5, wherein said pressureregulator is of a probe regulator type.
 7. The system of claim 6,wherein said probe regulator provides a gas pressure reduction withinthe insertion assembly, so as to allow said phase separation membrane toremove entrained liquids in the gas stream at prevailing processpressure and temperature, and without a reduction in gas pressure.
 8. Asystem for obtaining a sample of gas from a fluid stream of gas havingentrained liquid in a passage, comprising: an insertion assembly havingfirst and second ends, and a fluid conduit formed therethrough; ahousing having first and second ends, said housing formed to receivesaid insertion assembly; a valve associated with said housing, saidvalve formed to open when said housing receives said insertion assembly,so as to allow the gas from said passage to pass therethrough; saidinsertion assembly further comprising a phase separation membrane havingfirst and second sides, said first side of said phase separationmembrane formed to receive said gas from said valve, said second side ofsaid phase separation membrane communicating with said fluid conduitformed through said insertion assembly; said phase separation membraneformed to allow the passage of gas therethrough, while coalescingentrained liquid from said gas, so as to provide filtered gas from saidsecond side of said phase separation membrane to said fluid conduitformed through said insertion assembly, while providing coalesced liquidat said first side of said phase separation membrane.
 9. The system ofclaim 8, wherein there is further provided analysis means for analyzingsaid filtered gas, providing filtered gas analysis data.
 10. The systemof claim 8, wherein said valve comprises a poppet valve having a stemhaving first and second ends, the first end affixed to a biased poppetbody sealingly engaging a valve seat, said second end of said stemconfigured to engage said first end of said insertion assembly as saidinsertion assembly is inserted into said housing, so as to urge saidpoppet body from said valve seat, opening said valve upon insertion ofsaid insertion assembly, and closing said valve upon removal of saidinsertion assembly from said housing.
 11. The system of claim 10,wherein said poppet valve forms a drain means to allow coalesced liquidfrom said first side of said phase separation membrane to drain throughsaid poppet valve to said passage when said insertion assembly isinserted in said housing.
 12. The system of claim 11, wherein said gasand said fluid stream has a fluid pressure, and wherein said fluidpressure of said gas within said housing assembly upstream of said phaseseparation membrane is maintained at generally the prevailing pressureof said fluid stream.
 13. The system of claim 12, wherein said gas andsaid fluid stream has a fluid temperature, and wherein said fluidtemperature of said gas within said housing assembly upstream of thephase separation membrane is maintained at generally the prevailingtemperature of said fluid stream.
 14. The system of claim 11, whereinsaid housing assembly has a first end which communicates with said fluidstream, and wherein said phase separation membrane is contained withinsaid first end of said insertion assembly.
 15. The system of claim 11,wherein said insertion assembly may be retracted from said housing, andwherein said valve assembly is actuated to a closed position when saidinsertion assembly is retracted from said housing.
 16. The system ofclaim 11, wherein there is provided a local atmosphere exterior saidinsertion assembly, and wherein there is further provided a second fluidbarrier situated between said insertion assembly and said localatmosphere so as to provide fluid isolation between said fluid streamand said local atmosphere, at all times when said valve is actuated inan open position.
 17. The system of claim 10, wherein said gas has afluid pressure, and wherein there is further provided means formaintaining said fluid pressure of said gas sample upstream of saidphase separation membrane at about the same fluid pressure as said fluidpressure of said fluid stream.
 18. The system of claim 17, wherein saidfluid stream is enveloped in a conduit comprising a pipe having asidewall, said sidewall has formed therethrough a threaded aperture, andsaid housing has an outer wall having threads formed therein forengaging said threaded aperture.
 19. The system of claim 18, whereinsaid housing has a bore formed therein to receive said insertionassembly, the bore having first threads formed therein, and saidinsertion assembly has an outer wall having second threads to engagesaid first threads of the bore formed in said insertion assembly. 20.The system of claim 19, wherein said housing and said bore threadinglyengage in sealed fashion via first and second O-rings associated withsaid first and second threads, respectively.
 21. The system of claim 20,wherein said insertion assembly further has laterally emanatingtherefrom a guide rod configured to engage a slot formed in said housingto prevent rotation of said insertion assembly as it is inserted into orwithdrawn from said housing.
 22. The system defined in claim 21 whereinsaid gas has a pressure, and wherein said pressure is reduced at a pointin close proximity to a location where said insertion assemblyintersects said pipe.
 23. The system of claim 20, wherein there isfurther provided analysis means for analyzing said filtered gas,providing filtered gas analysis data.
 24. The system of claim 20,wherein said regulator valve comprises a ball and seat situated in saidfluid conduit formed through said insertion assembly, said ball and seatsituated adjacent to said phase separation membrane, and between saidphase separation membrane and said second end of said insertionassembly.
 25. The system of claim 19, wherein said valve is actuated toan open position when said insertion assembly is inserted into saidhousing.
 26. The system defined in claim 19 wherein said gas has apressure, and wherein said pressure is regulated internal to the saidinsertion assembly downstream of said phase separation membrane.
 27. Thesystem defined in claim 19 wherein said gas has a pressure, and whereinsaid pressure is regulated at a point in close proximity to the locationwhere said insertion assembly intersects said pipe.
 28. The system ofclaim 18, wherein said valve forms an open passageway which is not lessthan 0.1 inch across at any point, and said passageway has a crosssectional area of not less than 0.05 square inches.
 29. The system ofclaim 10, wherein said fluid stream and said gas sample has atemperature, and wherein there is further provided temperatureregulation means for maintaining said temperature of said gas sampleupstream of said phase separation membrane at the same temperature assaid temperature of said fluid stream.
 30. The system of claim 29,wherein said housing is contained within a thermally insulated housingcavity, and wherein said insertion assembly being maintained at atemperature which is essentially the prevailing process gas temperatureby heat transfer between said housing assembly and the process gassource.
 31. The system of claim 29, wherein said fluid conduit isconfigured to transfer heat from said fluid stream through a portion ofsaid housing, so as to offset heat loss from said housing assembly. 32.The system of claim 31, wherein one end of said housing communicateswith said fluid stream.
 33. The system defined in claim 10 wherein saidgas has a pressure, and wherein said pressure is reduced internal to thesaid insertion assembly downstream of said phase separation membrane.34. A system for retrieving a gas phase sample from a passage containinggas having liquid entrained therein, comprising: an insertion assemblyhaving first and second ends, and a fluid conduit formed therein; ahousing having first and second ends, said housing formed to receivesaid insertion assembly; a valve associated with said housing, saidvalve formed to open when said housing receives said insertion assembly,so as to allow the gas from said passage to pass therethrough, providingsample gas, said valve formed to close when said insertion assembly isremoved from said housing; said insertion assembly further comprising aphase separation membrane having first and second sides, said first sideof said phase separation membrane formed to receive said sample gas,said second side of said phase separation membrane communicating withsaid fluid conduit formed through said insertion assembly; said phaseseparation membrane formed to allow the passage of gas from said gassample therethrough, while coalescing entrained liquid from said gassample, so as to provide filtered gas from said second side of saidphase separation membrane to said fluid conduit formed through saidinsertion assembly, while providing coalesced liquid at said first sideof said phase separation membrane.
 35. The system of claim 34, whereinsaid valve comprises a poppet valve having a stem having first andsecond ends, the first end affixed to a biased poppet body sealinglyengaging a valve seat, said second end of said stem configured to engagesaid first end of said insertion assembly as said insertion assembly isinserted into said housing, so as to urge said poppet body from saidvalve seat, opening said valve upon insertion of said insertionassembly, and closing said valve upon removal of said insertion assemblyfrom said housing.
 36. The system of claim 35, wherein said poppet valveforms a drain means to allow coalesced liquid from said first side ofsaid phase separation membrane to drain through said poppet valve tosaid passage when said insertion assembly is inserted in said housing.37. The system of claim 36, wherein said poppet valve is situated in ahousing threadingly engaging said first end of said housing.
 38. Thesystem of claim 37, wherein the passage comprises a pipe having asidewall, said sidewall has formed therethrough an aperture, and saidhousing has an outer wall formed to engage the aperture formed in saidsidewall of said pipe.
 39. The system of claim 37, wherein said housinghas a bore formed therein to receive said insertion assembly, the borehaving first threads formed therein, and said insertion assembly has anouter wall having second threads to engage said first threads of thebore formed in said insertion assembly.
 40. The system of claim 39,wherein said housing and said bore threadingly engage in sealed fashionvia first and second O-rings associated with said first and secondthreads respectively.
 41. The system of claim 35, wherein said insertionassembly further has laterally emanating therefrom a guide rodconfigured to engage a slot formed in said housing to prevent rotationof said insertion assembly as it is inserted into or withdrawn from saidhousing.
 42. The system of claim 41, wherein said guide rod and slotformed in said insertion assembly and housing, respectively furthercooperate to insuring that said poppet valve is not over compressed. 43.The system of claim 34, wherein the fluid conduit formed in saidinsertion assembly is configured to direct filtered gas from theinsertion assembly.
 44. The system of claim 34, wherein said insertionassembly further comprises a regulator valve communicating with thefluid conduit formed in said insertion assembly, so as to control thepressure of gas in said fluid conduit and in the vicinity of said fluidseparation membrane.
 45. The system of claim 44, wherein said regulatorvalve is adjustable.
 46. The system of claim 45, wherein said regulatorvalve is of a probe regulator type.
 47. The system of claim 46, whereinsaid probe regulator provides a gas pressure reduction within theinsertion assembly, so as to allow said phase separation membrane toremove entrained liquids in the gas stream at prevailing processpressure and temperature, and prior to any reduction in gas pressure.48. The System of claim 47, wherein said regulator valve comprises aball and seat situated in said fluid conduit formed through saidinsertion assembly, said ball and seat situated adjacent to said phaseseparation membrane, and between said phase separation membrane and saidsecond end of said insertion assembly.